Thousands of activists, church-backed groups and opposition leaders called on Philippine President Gloria Macapagal Arroyo to resign on Saturday over corruption allegations.
Watched closely by hundreds of baton-wielding anti-riot police, the protesters sang songs and chanted slogans calling for Ms Arroyo to step down to avoid dividing the country and prevent a slide into anarchy.
"She should consider quitting voluntarily," said Ms Linda Cordova, a mother of three. "For the good of the country, for the good of the people, Arroyo has to go now."
Red, yellow, white and blue banners, representing several groups opposed to Ms Arroyo, provided shade from the scorching sun as 5,000 protesters listened to fiery speeches by opposition leaders at a public park before dispersing peacefully. "These wayward elements hate the president but we ask them: Do they have an alternative leader or platform of government to offer," Ms Arroyo's spokesman Ignacio Bunye said in a statement on Saturday.
He said the president was unperturbed by the latest tactics employed by her critics to derail her reform agenda.
Ms Arroyo hosted a diplomatic reception on Saturday after trying to consolidate her own supporters, holding meetings with hundreds of local officials, leaders of her political party and with a group of Protestant ministers.
Hundreds of anti-riot teams had fanned out across the Philippine capital on Saturday ahead the rally, which was organized by the Roman Catholic Church, a powerful force in the country of 80 million people, the majority of them Catholics.
Soldiers were also guarding highways leading to the capital, and the presidential palace has been turned into a fortress, ringed with barbed wire, while container trucks blocked the main road to the country's seat of power.
A Senate inquiry has heard allegations that Ms Arroyo's husband, son and brother-in-law took kickbacks from illegal gambling. This week, audio recordings surfaced that the opposition said bolstered its claims Arroyo cheated in last year's election.
The Roman Catholic Church has expressed anger over what it says is rampant corruption in Ms Arroyo's government and has exposed what it believes are links between the president's family and illegal gambling.